1. Field of the Invention
The present invention relates to a method of ultrasonic mounting that bonds a semiconductor chip to a substrate and an ultrasonic mounting apparatus using the same.
2. Related Art
When flip-chip bonding and mounting a semiconductor chip on a circuit board, a method is used that places electrode terminals, such as bumps, of the semiconductor chip in contact with electrode terminals, such as pads, of the circuit board and applies ultrasonic vibration to the semiconductor chip to bond the electrode terminals of the semiconductor chip and the circuit board together.
Conventionally, around 50 kHz is used as the frequency of the ultrasound applied to the semiconductor chip.
However, the present inventors have discovered that a large amount of bonding energy is obtained when ultrasound with a high frequency of around 200 kHz is used, which means that the mounting efficiency can be increased.
During ultrasonic mounting, vibration is applied from an ultrasonic vibrator to the semiconductor chip via a horn, and to transmit a large amount of vibration energy, the horn is provided with a convex part of a required width at a position corresponding to the loop (maximum amplitude point) of the vibration caused by the ultrasonic vibration and the semiconductor chip is placed in contact with this convex part to transmit the vibration energy.
When high-frequency ultrasound is used, there is a corresponding reduction in wavelength. Accordingly, the width of the convex part provided corresponding to the maximum amplitude point inevitably becomes narrow, so that there is the new problem that only small semiconductor chips can be mounted.